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1.
Laboratory experiments were conducted to determine the effects of methoxychlor on the larval development of the mud-crab, Rhithropanopeus harrisii, and the commercial blue crab, Callinectes sapidus, from the time of hatching until the 1st crab stage was reached. The effect of a range of concentrations of methoxychlor on survival of larvae of C. sapidus and R. harrisii was determined, as well as the concentrations which were sublethal and lethal. Since concentrations as low as 1.3, 1.6 and 1.9 ppb (μg l?1) methoxychlor were acutely toxic to C. sapidus larvae, and it took a concentration as high as 7.0 ppb to be acutely toxic to R. harrisii larvae, it was concluded that C. sapidus larvae were much more sensitive to methoxychlor than R. harrisii larvae. Zoeal and total development to the 1st crab stage of R. harrisii and C. sapidus were prolonged in relation to increased concentrations of methoxychlor. The developmental stages in which larvae were particularly sensitive varied in the two species. Methoxychlor residues of R. harrisii and C. sapidus larvae reared in concentrations of methoxychlor were determined.  相似文献   

2.
The effects of 0.01, 0.1, 1.0 and 10.0 ppb mirex on the development of blue crabs,Callinectes sapidus, from hatching to first crab stage are described. None of the concentrations of mirex showed any appreciable effect on the larvae during the first five days. Thereafter 0.01 ppb and 0.1 ppb mirex were found to be sublethal. These concentrations had no effect on the duration of development from hatching to megalopa or from hatching to first crab stage. Concentrations of 1.0 ppb and 10.0 ppb mirex proved to be acute. No one stage of development was particularly sensitive to 0.01 ppb mirex, but in the other three concentrations some stages were more sensitive (statistically) than others. The results of residue analyses are given for larvae reared in four concentrations of mirex at different periods of development. Residues of mirex in developmental stages increased with concentration, but biological magnification was greatest in larvae reared in the lowest concentration of mirex and lowest in larvae reared in the highest concentration.  相似文献   

3.
Survival of Rhithropanopeus harrisii larvae from hatching to first crab stage occurred in Na2CrO4 concentrations from 1.1 to 29.1 ppm. Estimated LC50 for complete zoeal development was 17.8 ppm Na2CrO4 and it was 13.7 ppm for development to first crab stage. A concentration of 1.1 ppm Na2CrO4 was nontoxic, while Na2CrO4 concentrations of 7.2 and 14.5 ppm were sublethal and concentrations of 29.1 to 58.1 ppm were acutely toxic. Low concentrations of Na2Cr04 caused an increase in swimming speed and high concentrations caused a decline. Survival of Callinectes sapidus larvae occurred in Na2CrO4 concentrations from 1.1 to 4.7 ppm. The LC50 for complete zoeal development was estimated to be 2.9 ppm Na2CrO4 and the LC50 for development to first crab stage was estimated to be 1.0 ppm Na2CrO4 The total Cr in sodium chromate is 32% by weight (Tacey,1981), hence, the total Cr concentrations tested were 32% of the Cr salts given above. Statistical analyses of the data on survival, duration and mortality of larvae are presented.  相似文献   

4.
The mud aqueous fraction (MAF) and suspended particulate phase (SPP) of low-density lignosulfonate type mud with úerrochrome added were nontoxic to larvae during the complete larval development of Rhithropanopeus harrisii. Five percent (5000 ppm, 0.5 % v/v mud in water) MAF and SPP were not toxic to Callinectes sapidus. Survival of C. sapidus larvae decreased as concentrations of MAF and SPP increased from 5 % (5000 ppm, 0.5 v/v mud in water) to 50% (50000 ppm, 5 % v/v mud in water). No larvae reached the 1st crab stage in 100% (100000 ppm, 10% v/v mud in water) MAF and SPP. Statistical analysis of the data on survival, mortality, and behavior are presented. Blue crab larval behavior is affected by exposure to MAF and SPP with the general effect being a decline in swimming speed. A significant reduction was only observed in 100% MAF but was noticed in 5, 25, 50, and 100% SPP.  相似文献   

5.
The effects of mirex, a chlorinated hydrocarbon used to kill the imported red ant, Solenopsis saevissima richteri, on the complete larval development of two crabs, Rhithropanopeus harrisii and Menippe mercenaria are described. The duration of developmental stages of Rhithropanopeus and the total time of development is generally lengthened with an increase in concentration of mirex from 0.01 to 10.0 ppb. There are highly significant differences between survival of larvae in the control and in each concentration of mirex. In Menippe, there were no pronounced differences in duration of developmental stages with increased concentrations of mirex, but the percentage of extra 6th zoeae was greater as concentrations were increased. There was differential survival of the developmental stages in relation to concentration of mirex, and Menippe larvae were much more sensitive to mirex than Rhithropanopeus larvae, especially in the megalopal stage. Residue analysis revealed that Menippe concentrates mirex more efficiently during development to crab stages than does Rhithropanopeus.  相似文献   

6.
Both swimming speeds and phototaxis by the four larval stages of the crab Rhithropanopeus harrisii were monitored upon chronic exposure to sublethal concentrations of the insect growth regulators methroprene (AltosidR: ZR-515), hydroprene (AltozarR: ZR-512) and dimiline (TH-6040). Larvae were reared under conditions of salinity (20orbo) and temperature (25°C) which produce the greatest developmental success. Sublethal concentrations of methroprene had no effect on swimming rates or phototaxis as compared to the acetone control larvae. For hydroprene, swimming rates by stage I, II and III zoeae were unaffected while a significant increase in swimming speeds occurred in Stage IV zoeae exposed to concentrations of 0.05 and 0.1 ppm. Only Stage III zoeae exposed to 0.l ppm showed a significant decrease in the level of positive phototaxis. Dimilin was much more potent, as significant increases in swimming speeds occurred in Stage I, II and III zoeae, with 0.3 ppb being the lowest effective concentration. Although swimming by Stage IV zoeae was unaffected, phototaxis was altered at concentrations as low as 0.1 ppb. Concentrations, which alter behavior, are related to levels which are reported to control mosquitoe larvae.  相似文献   

7.
Mud crab larvae, Rhithropanopeus harrisii were exposed to tributyltin oxide, (TBTO) (0.5, 1, 5, 10, 15, or 25 μg l?1) or tributyltin sulfide (TBTS) (0.5, 1, 5, 20, 30, or 50 μg l?1). Differential survival was observed in TBTO concentrations equal to or greater than 10 gg l?1 and in TBTS concentrations equal to or greater than 20 μg l?1 Growth and development rate were assessed as sublethal indices of stress. Of the two, development rate was more sensitive. All groups exposed to either compound had slower development rates than controls. Growth of the larvae, as shown by weight gain, was slightly increased in low exposures (a hormetic response) and decreased significantly in higher concentrations. The mean weight of the 50 μg l?1 TBTS group showed the largest decrease, to 57% of the control. The hormesis response was further examined by measuring daily growth of the zoeae. All groups exposed to tributyltin compounds showed an initial growth lag. The hormesis response occurred in the fourth zoeal stage or megalops. While R. harrisii is relatively tolerant to the acute toxicity of tributyltin compounds compared to other marine crustaceans tested, sublethal responses occur in very low concentrations. This points to the need for analyses to characterize tributyltin environmental concentrations.  相似文献   

8.
Tropospheric O3 (ozone) stress can negatively affect forest productivity and crop yields. Yet, relatively little attention has been paid to the effects of O3 stress on belowground system. Here, a pot experiment was conducted in open top chambers to monitor the response of physico-chemical properties, main microbial groups, and potential enzyme activities of a soil cropped to soybean (Glycine max; a highly sensitive species to O3) and exposed to background O3 concentration (45?±?5 ppb, control) and O3 stress (80?±?10 ppb, O3+ and 110?±?10 ppb, O3++) with sampling at branching, flowering, and podding stages. The growth of soybean was significantly inhibited by O3 stress, which showed significant effects on soil microbial biomass C and pH during the whole growth of soybean at the highest concentration. The O3++ stress significantly decreased soil pH at flowering stage, and increased soil pH at podding stage; the O3+ stress and growth stage?×?O3+ stress showed significant influences on the potential activities of acid phosphomonoesterase, invertase, and amylase. The O3 stress significantly reduced the abundances of total PLFAs (phospholipid fatty acid), bacterial PLFAs, and AMF (arbuscular mycorrhizal) PLFAs at branching and podding stages. Our results suggest that the main soil microbial groups might be indirectly affected by the O3 stress through the alteration of soil physico-chemical properties with changes in the potential enzyme activities of soil.  相似文献   

9.
Effect of malathion (organophosphorus insecticide) and endosulfan (organochlorine insecticide) on in vitro LH-induced oocyte maturation was investigated in the oocytes of common carp, Cyprinus carpio. In control incubation, LH at the concentration of 10 μg mL?1 induced 41.2 ± 1.6% of germinal vesicle breakdown (GVBD). When the oocytes were incubated with malathion at the concentrations of 1000, 500, 100, and 50 ppb together with LH it could induce only 13.4 ± 0.4, 14.0 ± 1.0, 12.9 ± 3.5, and 18.1 ± 3.9% of GVBD, respectively. Similarly, when the oocytes were incubated with endosulfan at the concentrations of 0.5, 0.1, 0.05, and 0.01 ppb together with LH, it induced only 12.8 ± 1.6, 8.8 ± 1.2, 20.9 ± 2.1 and 26.0 ± 2.2% of GVBD, respectively. The significance of the result obtained were discussed on the basis of available literature.  相似文献   

10.
The objective of the present study was to evaluate the relationships between the quantity, toxicity, and compositional profile of dioxin/furan compounds (PCDD/Fs) and dioxin-like polychlorinated biphenyls (DL-PCBs) in estuarine sediment and in the blue crab (Callinectes sapidus). Sediment and blue crab samples were collected in three small urban estuaries that are in relatively close proximity to each other. Results show that differences between PCDD/F and DL-PCB mass concentrations and total toxic equivalents (TEQ) toxicity in sediments of the three estuaries are reflected in those of the blue crab. TEQs are higher in the hepatopancreas of the crabs than in the sediment, but the concentration factor is inversely proportional to the TEQ in the sediments. Congener profiles in the crabs are systematically different from those in the sediments, and the difference is more pronounced for PCDD/Fs than for DL-PCBs, possibly due to differences in metabolization rates. Compared with sediment profiles, more lesser-chlorinated PCDD/Fs that have higher TEFs accumulate in crab hepatopancreas. This selective bioaccumulation of PCDD/Fs results in a TEQ augmentation in crab hepatopancreas compared with sediments. The bioaccumulation in the blue crab is also selective for PCDD/Fs over DL-PCBs.  相似文献   

11.
The effect of oil and oil products on the 5 species of crustaceans in the Caspian sea was investigated. Two species of shrimp (Palaemon elegans, P. adspersus), crab (Thithropanopeus harrisii tridentatus), amphipoda (Pontogammarus maeoticus), and cirripeda crayfish (Balanus improvisus) are classified among them. Various oil products (oil, phenol, fuel oil, xerosene, gasoline, solar oil) were used in the experiments. The influence of oil on the respiration and mass increase, quality of generation, and larval stages of the crustaceans was studied. Minimal critical concentrations for the crustaceans are 0.001 mg L?1 of fenol, 0.4 mg L?1 of oil, 0.1 mg L?1 of solar oil, 0.01 mg L?1 of gasoline and fuel oil.  相似文献   

12.
Mercury deposition was monitored at two mountain sites in Quebec using transplanted lichens and moss. The terricolous lichen species Cladina rangiferina, the epiphytic lichen species Hypogymnia physodes, and the feather moss Pleurozium schreberi were transplanted from a northern Ontario boreal site to the bases and summits of Roundtop Mountain and Mt. Tremblant in southern Quebec. After 12 months, transplants of C. rangiferina sited at the base and summit of Roundtop mountain and the summit of Mt. Tremblant showed a significant increase in mercury concentration over controls (p < 0.05). The largest difference occurred at the summit of Roundtop mountain where mercury concentration was 81.4 ± 10.9 ppb as compared to 45.6 + 10.6 ppb at the control site. No significant increases in mercury concentration in P. schreberi were seen after 12 months at any site althought trends of increase were apparent. After 20 months, further significant increases in Hg content were observed in both the terricolous lichen and the feather moss at both the Roundtop Mountain base and summit sites. A significant increase in Hg content of P. schreberi was also noted at the Mt. Tremblant summit site. Over the length of the study the greatest mercury concentration increases were observed in the feather moss at the Roundtop Mountain summit site (with a 248.3 ± 30.0 ppb mercury concentration as compared to 108.3 ± 30.0 ppb in controls). No significant change in mercury concentration in the epiphyte H. physodes was found during the study. These data indicate that mercury deposition is occurring, especially to higher elevation sites. While mercury inputs at the summits may be increased by the effects of fog, increases in mercury at the base sites cannot be accounted for the same way, but may represent the importance of dry deposition processes.  相似文献   

13.
The effect of ‘red mud’ at a dilution of 1:105 to 1:106 on growth, body weight and mortality of juvenile stages of the planktonic copepodCalanus helgolandicus were investigated. In the presence of phytoplanktonC. helgolandicus ingested large amounts of ‘red mud’. In comparison to control copepods growth of ‘red mud’ animals was delayed. Mortality of ‘red mud’ animals was 5 to 8 times higher than that of control animals. The dry body weight of C III, C v, and adults raised from N v/NVI on in ‘red mud’ was far lower than the dry weight of the control animals. All results show that ‘red mud’ at the above mentioned dilutions affects negatively juvenile stages and adults ofCalanus helgolandicus.  相似文献   

14.
Aphids are frequently found on conifers, but mass outbreaks are seldom reported. On trees stressed by air pollutants the natural resistance can be broken and insect attack combined with pollution stress may promote plant damages. To evaluate effects of air pollution on conifer aphids Scots pine and Norway spruce seedlings have been exposed to gaseous pollutants (O3, SO2 and NO2) in growth chambers. The studied aphid species were Cinara pilicornis Hartig on Norway spruce, C. pinea (Mordv.) and Schizolachnus pineti Fabr. on Scots pine in SO2 fumigations and S. pineti in O3 and NO2 fumigations. C. pilicornis nymphs had peaked dose response to SO2 concentration. Both the first and third instar larvae of C. pilicornis showed highest mean relative growth rate (MRGR) at 100 ppb SO2 concentration. MRGR of C. pinea peaked at 50 and 150 ppb SO2 The response of S. pineti was more inconsistent During fumigation the peak MRGR of S. pineti was at 100 ppb and after exposure at 50 ppb SO2. MRGR of S. pineti nymphs was not significantly affected during fumigation or after the end of fumigation experiment by 100 ppb O3 or 100 ppb NO2 or the mixtures. The results suggest that SO2 affects more distinctively on aphid performance on conifers than O3 or NO2. Especially stem-feeding aphids on spruce can exploit physiological disturbance of host plant under pollution stress.  相似文献   

15.
In conjunction with the start-up of a secondary wastewater treatment facility, population levels ofPrototheca sp. were measured. Wastewater influent levels ofPrototheca sp. were < 1 × 102 mL?1 whilePrototheca sp. trapped in the biological film reached levels > 1 × 105 mL?1. Effluent levels were only slightly less than influent levels because effluent contained the breaking off film. The film along with the primary sediment retained the high levels ofPrototheca sp. throughout the 20 day anaerobic digestion, however growth was not thought to occur. Depending on the method of flocculation, dewatering and disposal, various levels ofPrototheca sp. were returned to the environment in the sludge and effluent. The dynamic change in thePrototheca sp. population levels in the maturing film was thought to reflect the preference for the higher BOD influent. This change was manifest during the fourth month after start-up, as well as when comparing the film at the start with that at the end of the secondary treatment train. Prototheca sp. are ubiquitous inhabitants of all stages of domestic and municipal wastewater from the primary plumbing through all stages of primary and secondary treatment plant processes.Prototheca sp. were isolated from surface water and potable water, but were thought to represent wastewater contamination. SincePrototheca sp. are pathogenic for human beings and animals, wastewater presents a potential threat, but reported infections are rare and risk is minimal.  相似文献   

16.
不同灌溉处理下冬小麦水平衡与灌溉增产效率研究   总被引：6，自引：1，他引：5  
水资源是华北平原冬小麦、夏玉米种植区最重要的生产制约因素, 农业水资源高效利用具有重大的社会需要。通过设置冬小麦不同灌溉处理, 分析了各处理的水分平衡、产量和灌溉增产效率。结果显示: 1)不同灌溉处理具有不同的水分平衡过程, 雨养农田、充分灌溉处理、返青水胁迫处理、拔节抽穗水胁迫处理和灌浆水胁迫处理的蒸散量分别为251±58 mm、482±48 mm、352±44 mm、388±22 mm 和324±53 mm; 2)灌溉量对于小麦产量的增加具有明显的正效应, 拔节-抽穗水胁迫对作物产量有较大影响, 灌浆水胁迫和返青水胁迫均没有对小麦产量造成明显影响; 雨养农业的经济产量为2 950±635 kg·hm-2, 充分灌溉下的经济产量约为5 994±994 kg·hm-2; 冬小麦返青期、拔节抽穗期、灌浆期施加适度的水分胁迫, 产量分别为5 163±885kg·hm-2、5 047±1 180 kg·hm-2、5 249±975 kg·hm-2, 与充分灌溉相比, 没有明显的产量下降; 3)小麦的灌溉增产效率存在明显的年际差异, 在丰水年或特丰水年, 灌溉增产效率为1.9 kg·m-3, 在枯水年为0.4 kg·m-3, 平水年为1.6 kg·m-3。  相似文献   

17.
Arbuscular mycorrhizal (AM) fungi are recognized for their positive effects on plant growth, playing an important role in plant P nutrition. We used C16:1cis11 and C18:1cis11 fatty acid methyl ester (FAME) biomarkers to monitor the dynamics of AM fungi during the reproductive stages of maize (Zea mays L.) grown at high yield in Nebraska, USA. Two fields with four different levels of P availability were sampled throughout the reproductive stages. Chambers, made of PVC enclosed mesh fabric to allow passage of roots and hyphae (+R) or hyphae alone (-R) and amended with either KH2PO4(+P) or distilled water (-P), were installed in the field at tasselling and removed after three, six and nine weeks. Our objectives were (i) to provide evidence for C allocation to AM fungi during the reproductive stages of high productivity maize and (ii) to link AM fungal growth dynamics with changes in soil P availability. We observed that initial AM FAME concentration was lower at sites with a high availability of P. During the reproductive growth of maize, AM biomarkers increased inside the chambers and were consistent with the biomarker increase observed in adjacent field soil. This confirms that there is C allocation from the plant to the symbiont during the reproductive stages of maize. We also observed a reduction in available P in +R and -R chambers. This observation implies that hyphae were as efficient as roots and hyphae in reducing the P concentration in chambers. These results demonstrate that AM fungi are active during the reproductive growth stages of maize and may benefit high productivity maize crops by facilitating P uptake.  相似文献   

18.
Immobilized microbial cells for the biological treatment have the potential to degrade toxic chemicals faster than conventional wastewater treatment systems. In the present study, suitability of immobilized Pseudomonas fluorescens SM1 strain in calcium alginate beads for remediation of the major toxicants in Indian water bodies was tested by means of GC/HPLC and AAS techniques. Roughly 80% reduction in the concentration of phenols was observed by immobilized SM1 cells compared with 60% by the free cells. Also, in the case of the bioremediation of heavy metals, immobilized SM1 cells were found to be more efficient compared with the free cells. Suspension of P. fluorescens SM1 cells in the test model water for 24 h brought down the concentrations of Cu++, Cd++, Ni++, and Pb++ by more than 75% under free cell state and 7?C9% better efficiency under the immobilized conditions. However, Cr(VI) could show only 44% removal by the cell immobilized system, whereas a mere 35% reduction in the Cr(VI) levels was shown in the test model water by the free SM1 cells under the same conditions. Moreover, a model water containing 2,000 ppb of BHC, 1,248 ppb mancozeb, and 312 ppb 2,4-D passed through the cell immobilized column resulted in the decline in their concentrations up to 362 ppb, 750 ppb, and 126 ppb, respectively. Generally, AAS, HPLC, and GC analyses of treated test model waters with the free and immobilized SM1 cells exhibited high potential of immobilized SM1 in detoxification of test water. From the results, we conclude that immobilized cells of P. fluorescens SM1 strain were quite effective in bioremediation of major toxicants present in Indian water bodies, and we also recommend the use of immobilized bacterial cells rather than the free cells for the bioremediation/detoxification process.  相似文献   

19.
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20.
Antibiotics from various sources such as livestock waste are being accumulated in the soil. The excessive uptake of antimicrobial agents by plants has been a major concern as it is currently unknown how plants respond to the presence of antibiotics in agricultural lands. The objectives were to analyze the alteration of trigonelline (TRG) biosynthesized by plants in response to various antibiotic stresses and to evaluate the ability of peanut (Arachis hypogaea L.) plants to resist the deleterious impacts of antibiotic uptake. Three veterinary antibiotics used in this study were tetracycline, streptomycin sulfate, and chloramphenicol in the concentrations of 2.5 and 5 mg L?1. Mean TRG amounts were 53.4 ± 1.6 and 59.9 ± 1.1 μg·g?1 dry weight (DW) in Spanish as treated with growth chloramphenicol and streptomycin at 2.5 mg·L?1, respectively, and were significantly (p ≤ .05) different compared to the control (40.4 ± 1.6 μg·g?1 DW) of Spanish. Spanish genotype treated with chloramphenicol at 5 mg·L?1 had a mean TRG amount of 41.0 ± 1.0 μg·g?1 DW and improved yield, with the average pod number of 29.6 ± 7.6 and pod weight of 20.1 ± 6.1 g. TRG was continuously biosynthesized and increased under antibiotic stress up to 12.7% at full pod (R4 growth stage) and 139.1% at beginning maturity (R7), but declined 20.2% at the harvest stage (R8) in all combined genotypes when compared with TRG amounts (21.7 ± 0.6 μg·g?1 DW) at the flowering R1 stage.  相似文献   

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